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Income Taxes - Additional Information (Detail) - USD ($)
$ in Millions
9 Months Ended
Jan. 29, 2016
Jan. 23, 2015
Apr. 24, 2015
Apr. 25, 2014
Income Tax Contingency [Line Items]        
Federal research credit benefit $ 7 $ 6    
Gross unrecognized tax benefits 216 275 $ 272 $ 236
Unrecognized tax benefits included in other long-term liabilities 160      
Unrecognized tax benefits that would affect provision for income taxes 153      
Federal Income Tax        
Income Tax Contingency [Line Items]        
Resolution of income tax examinations 23 47    
Retroactive Research Credit        
Income Tax Contingency [Line Items]        
Federal research credit benefit $ 4 $ 4